/**
 * 密码哈希工具
 * 使用 SHA-256 对密码进行哈希处理
 */

/**
 * 纯 JavaScript 实现的 SHA-256（兼容所有浏览器环境）
 * 来源：简化版本，符合 SHA-256 标准
 */
function sha256Pure(message: string): string {
  // 初始化哈希值
  const K = [
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
    0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
    0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
    0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
    0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
    0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
    0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
  ];

  const utf8Encode = new TextEncoder();
  const messageBytes = utf8Encode.encode(message);
  const messageBits = messageBytes.length * 8;

  // 填充消息
  const paddedLength = Math.ceil((messageBits + 65) / 512) * 64;
  const padded = new Uint8Array(paddedLength);
  padded.set(messageBytes);
  padded[messageBytes.length] = 0x80;

  // 添加消息长度
  const view = new DataView(padded.buffer);
  view.setUint32(paddedLength - 4, messageBits & 0xffffffff, false);

  // 初始化哈希值
  let h0 = 0x6a09e667, h1 = 0xbb67ae85, h2 = 0x3c6ef372, h3 = 0xa54ff53a;
  let h4 = 0x510e527f, h5 = 0x9b05688c, h6 = 0x1f83d9ab, h7 = 0x5be0cd19;

  // 处理每个512位块
  for (let chunk = 0; chunk < paddedLength; chunk += 64) {
    const w = new Uint32Array(64);
    for (let i = 0; i < 16; i++) {
      w[i] = view.getUint32(chunk + i * 4, false);
    }
    for (let i = 16; i < 64; i++) {
      const s0 = ((w[i - 15] >>> 7) | (w[i - 15] << 25)) ^ ((w[i - 15] >>> 18) | (w[i - 15] << 14)) ^ (w[i - 15] >>> 3);
      const s1 = ((w[i - 2] >>> 17) | (w[i - 2] << 15)) ^ ((w[i - 2] >>> 19) | (w[i - 2] << 13)) ^ (w[i - 2] >>> 10);
      w[i] = (w[i - 16] + s0 + w[i - 7] + s1) >>> 0;
    }

    let a = h0, b = h1, c = h2, d = h3, e = h4, f = h5, g = h6, h = h7;

    for (let i = 0; i < 64; i++) {
      const S1 = ((e >>> 6) | (e << 26)) ^ ((e >>> 11) | (e << 21)) ^ ((e >>> 25) | (e << 7));
      const ch = (e & f) ^ (~e & g);
      const temp1 = (h + S1 + ch + K[i] + w[i]) >>> 0;
      const S0 = ((a >>> 2) | (a << 30)) ^ ((a >>> 13) | (a << 19)) ^ ((a >>> 22) | (a << 10));
      const maj = (a & b) ^ (a & c) ^ (b & c);
      const temp2 = (S0 + maj) >>> 0;

      h = g;
      g = f;
      f = e;
      e = (d + temp1) >>> 0;
      d = c;
      c = b;
      b = a;
      a = (temp1 + temp2) >>> 0;
    }

    h0 = (h0 + a) >>> 0;
    h1 = (h1 + b) >>> 0;
    h2 = (h2 + c) >>> 0;
    h3 = (h3 + d) >>> 0;
    h4 = (h4 + e) >>> 0;
    h5 = (h5 + f) >>> 0;
    h6 = (h6 + g) >>> 0;
    h7 = (h7 + h) >>> 0;
  }

  // 输出哈希值
  return [
    h0.toString(16).padStart(8, '0'),
    h1.toString(16).padStart(8, '0'),
    h2.toString(16).padStart(8, '0'),
    h3.toString(16).padStart(8, '0'),
    h4.toString(16).padStart(8, '0'),
    h5.toString(16).padStart(8, '0'),
    h6.toString(16).padStart(8, '0'),
    h7.toString(16).padStart(8, '0')
  ].join('');
}

/**
 * 将字符串转换为 SHA-256 哈希
 * @param message 要哈希的字符串
 * @returns 十六进制格式的哈希值
 */
export async function sha256(message: string): Promise<string> {
  // 优先使用纯JS实现，以确保在所有环境下都可用（包括局域网IP访问）
  try {
    return sha256Pure(message);
  } catch (error) {
    console.error('[PasswordHash] 纯JS SHA-256实现失败:', error);
    
    // 如果纯JS实现失败，尝试使用 Web Crypto API
    if (typeof crypto !== 'undefined' && crypto.subtle) {
      try {
        const msgBuffer = new TextEncoder().encode(message);
        const hashBuffer = await crypto.subtle.digest('SHA-256', msgBuffer);
        const hashArray = Array.from(new Uint8Array(hashBuffer));
        return hashArray.map(b => b.toString(16).padStart(2, '0')).join('');
      } catch (cryptoError) {
        console.error('[PasswordHash] Web Crypto API失败:', cryptoError);
      }
    }
    
    // 如果所有方法都失败，抛出错误
    throw new Error('无法计算SHA-256哈希');
  }
}

/**
 * 对密码进行哈希处理
 * @param password 明文密码
 * @returns 哈希后的密码
 */
export async function hashPassword(password: string): Promise<string> {
  return await sha256(password);
}
